The present invention relates in general to differential inter-fluid contact equipment to provide contact between gases, between liquids or between gas and liquid for various industrial purposes, such as packed towers for distillation, absorption, cooling and desorption (stripping). More particularly, the invention is concerned with a packing or packing material filling such packed towers.
In the art of inter-fluid contactors such as distillation, absorption, cooling and desorption towers or columns, various types of packings made of ceramics, glass, synthetic resin, or metal, are known as materials which fill the towers for higher efficiency of contact between different gases or liquids, or between gas(es) and liquid(s). Those packing materials which fill a packed tower are either dumped in random into a tower or stacked in order in the tower. In other words, the packings are arranged either in an irregular or dumped fashion in the form of pellets, or in cylindrical, planar or other forms, or in a regular or stacked fashion in the form of grids or honeycombs. Different kinds of fluids to be treated for contact with each other are adapted to flow through those irregularly or regularly arranged packings. It is a recognized requirement that the packings assure a minimum pressure loss or drop of the fluids during their flow through the tower, as well as provide an improved efficiency of contact between the flowing fluids.
A known advantage of the dumped packing materials of cylindrical or planar shapes or in the form of pellets, lies in that they are easily loaded into a tower, i.e., a random arrangement of the packing materials within the tower is sufficient for filling the tower with the packing. On the other hand, however, such random or dumped packing arrangement causes an operational problem which occurs, for example, when a gas-liquid contact is effected in a countercurrent manner, more specifically, in such a manner that liquid flows downward through the packing from the top of a tower while gas flows upward through the packing from the bottom of the tower. In this instance, surfaces of the dumped packing material arranged in random cause complicated turbulent countercurrent flows of the fluids, thereby contributing to improvement in efficiency of gas-liquid contact. With the traditional dumped packings within the tower, however, some of the channels or passages formed in a bed or layer of the individual packings are oriented so that they extend almost normal or orthogonal with respect to the longitudinal axis of the packed tower, i.e., to the line of flow of the fluids through the tower, whereby there are considerable chances of the fluid streams colliding with or impinging upon the outer wall surfaces of the packings. This phenomenon not only creates a tendency of the liquid to stay around the wall surfaces of the packings, but also leads to an increase in pressure loss of the upwardly flowing gas due to collision thereof with the surfaces of the packings. The above stay of the liquid and pressure loss of the gas will increase difficulty of the fluids to pass through the channels formed in the packings, and consequently reduce the contact efficiency of the fluids to be treated. These have been the recognized drawbacks associated with the traditional dumped packings of irregular or random arrangement.
In the case where a packed tower is filled with regularly stacked packings of grid or honeycomb type, the fluid flow channels formed in the packings are generally oriented substantially in parallel to the line of flow of the fluids through the tower. As a result, the pressure loss encountered with this regular arrangement is less than that experienced when pellet-type packings or other dumped packings are used. However, the stacked packings suffer a decrease of collision between liquid and gas, which results in a local blow or channelling of the gas without contacting the liquid, thereby reducing the liquid-gas contact efficiency. A further inconvenience of these stacked packings arises from their inherent requirement that the individual packing bodies be placed in the tower with predetermined orientation, which increases the cost for filling the tower.